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Discussion Starter #1
Hi all,

I have 3x Akasa Piranha front intake fans connected to the ASUS Maximus VIII Gene motherboard (CHA_FAN4) using a PWM 3 way splitter and 2x Akasa Piranha CPU fans connected using a 2 way splitter to CPU_FAN header, both are running the same fan profile in the BIOS however CHA_FAN4 fans are running 70-90RPM lower than the fans connected to the CPU_FAN header, is this normal?



Also, is it safe to connect 3 fans to the motherboard using a 3 way splitter or would that overload the fan header? The fan label at the back says 0.13A and I have checked the motherboard manual but it doesn't say the max fan power for chassis fan connectors.



Thanks
 

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Your set up (a simple splitter) is reporting multiple fan speeds to each PWM controller. The controller gets confused about what speed the fan(s) are really spinning at.

You need a set up that controls all the fans connected to a fan header from a single speed signal.

Something like this:



And, if you want each set of fans to run at different speeds (ie, each set controlled by a different motherboard fan header) you'll need two of the above.

And Swiftech isn't the only one that makes these things.
 

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Discussion Starter #3
Quote:
Originally Posted by billbartuska View Post

Your set up (a simple splitter) is reporting multiple fan speeds to each PWM controller. The controller gets confused about what speed the fan(s) are really spinning at.

You need a set up that controls all the fans connected to a fan header from a single speed signal.

Something like this:



And, if you want each set of fans to run at different speeds (ie, each set controlled by a different motherboard fan header) you'll need two of the above.

And Swiftech isn't the only one that makes these things.
I'm using this EK PWM 2 way splitter for 2x CPU fans connected to CPU_FAN header which only 1 fan reports the speed signal to the header as the other connector is 3 pin only.



And I'm using this EK PWM 3 way splitter for 3x front intake fans connected to CHA_FAN4 header but both headers are using the same Akasa Piranha fans but CHA_FAN4 fans are running 70-90RPM lower than CPU_FAN?



I prefer to use splitter cables rather than a PWM hub as it is better for my case cable management and I could set different fan profile in BIOS for the headers if I need to in the further.
 

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If we take your question and turn it into a statement, "Running different numbers of fans on splitters on different headers results in slight variances in speed.", it seems completely sensible. Different power draw, PWM signal reduced on one header, etc.
 
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